/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;
using Spring.Util;

namespace Spring.Core;

/// <summary>
/// Criteria that is satisfied if the <see cref="System.Type"/> of each of the
/// arguments matches each of the parameter <see cref="System.Type"/>s of a given
/// <see cref="System.Reflection.MethodInfo"/>.
/// </summary>
/// <remarks>
/// <p>
/// If no <see cref="System.Type"/> array is passed to the overloaded constructor,
/// any method that has no parameters will satisfy an instance of this
/// class. The same effect could be achieved by passing the
/// <see cref="Spring.Util.ObjectUtils.EmptyObjects"/> array to the overloaded constructor.
/// </p>
/// </remarks>
/// <author>Rick Evans</author>
/// <author>Bruno Baia</author>
public class MethodArgumentsCriteria : ICriteria
{
    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodArgumentsCriteria"/> class.
    /// </summary>
    public MethodArgumentsCriteria() : this(ObjectUtils.EmptyObjects)
    {
    }

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodArgumentsCriteria"/> class.
    /// </summary>
    /// <remarks>
    /// <p>
    /// If the supplied <paramref name="arguments"/> array is null, then this
    /// constructor uses the <see cref="System.Type.EmptyTypes"/> array.
    /// </p>
    /// </remarks>
    /// <param name="arguments">
    /// The <see cref="System.Object"/> array that this criteria will use to
    /// check parameter <see cref="System.Type"/>s.
    /// </param>
    public MethodArgumentsCriteria(object[] arguments)
    {
        _parameters = ReflectionUtils.GetTypes(arguments);
    }

    /// <summary>
    /// Does the supplied <paramref name="datum"/> satisfy the criteria encapsulated by
    /// this instance?
    /// </summary>
    /// <remarks>
    /// <p>
    /// This implementation respects the inheritance chain of any parameter
    /// <see cref="System.Type"/>s... i.e. methods that have a base type (or
    /// interface) that is assignable to the <see cref="System.Type"/> in the
    /// same corresponding index of the parameter types will satisfy this
    /// criteria instance.
    /// </p>
    /// </remarks>
    /// <param name="datum">The datum to be checked by this criteria instance.</param>
    /// <returns>
    /// True if the supplied <paramref name="datum"/> satisfies the criteria encapsulated
    /// by this instance; false if not or the supplied <paramref name="datum"/> is null.
    /// </returns>
    public bool IsSatisfied(object datum)
    {
        bool satisfied = false;
        MethodInfo method = datum as MethodInfo;
        if (method != null)
        {
            bool isParamArray = false;
            Type paramArrayType = null;
            ParameterInfo[] parametersBeingChecked = method.GetParameters();
            if (parametersBeingChecked.Length > 0)
            {
                ParameterInfo lastParameter = parametersBeingChecked[parametersBeingChecked.Length - 1];
                isParamArray = lastParameter.GetCustomAttributes(typeof(ParamArrayAttribute), false).Length > 0;
                if (isParamArray)
                {
                    paramArrayType = lastParameter.ParameterType.GetElementType();
                }
            }

            if (parametersBeingChecked != null
                && parametersBeingChecked.Length == _parameters.Length)
            {
                satisfied = true;
                for (int i = 0; i < _parameters.Length; ++i)
                {
                    Type sourceType = _parameters[i];
                    Type typeBeingChecked = parametersBeingChecked[i].ParameterType;
                    if (!typeBeingChecked.IsAssignableFrom(sourceType))
                    {
                        if (isParamArray && i == _parameters.Length - 1)
                        {
                            if (!paramArrayType.IsAssignableFrom(sourceType))
                            {
                                satisfied = false;
                                break;
                            }
                        }
                        else
                        {
                            satisfied = false;
                            break;
                        }
                    }
                }
            }
            else if (isParamArray && (_parameters.Length >= parametersBeingChecked.Length - 1))
            {
                satisfied = true;
                for (int i = 0; i < parametersBeingChecked.Length - 1; ++i)
                {
                    Type sourceType = _parameters[i];
                    Type typeBeingChecked = parametersBeingChecked[i].ParameterType;
                    if (!typeBeingChecked.IsAssignableFrom(sourceType))
                    {
                        satisfied = false;
                        break;
                    }
                }

                for (int i = parametersBeingChecked.Length - 1; i < _parameters.Length; ++i)
                {
                    Type sourceType = _parameters[i];
                    if (!paramArrayType.IsAssignableFrom(sourceType))
                    {
                        satisfied = false;
                        break;
                    }
                }
            }
        }

        return satisfied;
    }

    private readonly Type[] _parameters;
}
